1. Field of the Invention
The present invention relates to hot stabs that are used by ROVs. More particularly, the present invention the relates to leakage-preventing devices as used with hydraulic hoses.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
As offshore drilling and completion operations progress into deeper waters, especially into waters of greater than 1000 feet, many relatively simple surface operations become complex and costly. One frequent operational requirement is that of engaging a hydraulic stab sub receptacle with a probe for the purpose of applying hydraulic flow and pressure to operate a particular function. The function can be a valve, a blowout preventor, a test port, or other items.
These connections can be made by divers, by ROV's (Remotely Operated Vehicles) which are free swimming, or by manipulators that are guided into place. The probe that is used by these ROV's is commonly known as a “hot stab”.
One of the main problems with the existing hot stabs is that the hydraulic hose must be connected to the hot stab. During frequent manipulation of the hot stab by the ROV, the hydraulic hose can become twisted, contorted, or otherwise angularly displaced with respect to the hot stab probe. Presently, hydraulic hoses are connected to the hot stab probe by a fitting similar to that of a garden hose. In other words, there is a hose swivel that is joined to a threaded portion on the fluid conduit connector of the hot stab. The rotation of the hose swivel causes a crimp fitting at the end of the hydraulic hose to become engaged in surface-to-surface contact with an angled surface formed at the end of the fluid conduit connector of the hot stab.
Unfortunately, since a great deal of force can be applied to this relatively small connection, leaks are quite common in the area of the connection between the crimp fitting of the hydraulic hose and the fluid conduit connector of the hot stab. This particularly a problem when the hot stab is required to carry fluids delivered by relatively wide diameter and heavy hydraulic hoses. As manipulations continue, the likelihood of a leak becomes more pronounced. When these leaks occur, it is necessary for the ROV to travel to the surface for repair and maintenance. In each circumstance that the ROV is required to return to the surface, a great deal of time, expense and labor is wasted. As such, a very strong need has developed whereby the possibility of leakage from the connection between the hydraulic hose and the hot stab is effectively prevented.
In the past, various patents have issued relating to such hot stab connectors. For example, U.S. Pat. No. 4,682,913, issued on Jul. 28, 1987 to Shatto et al., describes a hydraulic stab connector. In particular, this patent discloses an apparatus and method for connecting a fluid conduit carried by an ROV to a fluid conduit of a subsea equipment assembly, such as a hydraulically-actuated device, in a non-binding manner. The apparatus includes a vacuum-locking device, such as a hydraulically-actuatable suction lock assembly, which is selectively actuatable to lock or unlock the apparatus with respect to the device of the assembly.
U.S. Pat. No. 4,695,190, issued on Sep. 22, 1987 to Best et al., teaches a pressure-balanced stab connection. This apparatus includes a stab member with a body having a bore therethrough. One end of the bore exits from the stab body through a side port. A stab receptacle includes a bore for receiving the stab body, and a flow bore intersecting the receiving bore and leading to the exterior of the receptacle. The side port communicates with the receptacle flow bore when the stab member is landed in the receiving bore. Seals above and below the side port seal the receiving bore above and below the intersection of the receptacle flow bore and receiving bore. The cross-sectional areas of the seals exposed to internal fluid pressure are substantially equal, resulting in zero blow-apart force on the stab connection.
U.S. Pat. No. 4,863,314, issued on Sep. 5, 1989 to B. F. Baugh, shows a hydraulic stab sub with multiple seals for use in remote and harsh environments. This hydraulic stab sub has the ability to move the seals radially inwardly to a retracted position in which the hydraulic stab sub can be easily inserted into a mating receptacle and alternately to move the seals radially outward to perform useful functions such as sealing or locking into the receptacle.
U.S. Pat. No. 4,878,783, issued on Nov. 7, 1989 to B. F. Baugh, shows a hydraulic stab sub connector with the angular freedom. This hydraulic stab sub is designed for use in remote and harsh environments. The stab sub is capable of being inserted into a close fitting receptacle at a relatively high angular mismatch by providing for radial relative movement of sealing rings and seal holding rings with reference to the centerline of the hydraulic stab sub.
U.S. Pat. No. 5,143,483, issued on Sep. 1, 1992 to W. H. Peterson, shows a hydraulic stab sub for use in a remote location that can be inserted into a receptacle with the seals in a retracted position. The seals are expanded to a sealing portion using hydraulic pressure while an hydraulic piston is provided for removing the stab sub from the receptacle.
U.S. Pat. No. 5,988,281, issued on Nov. 23, 1999 to Douglas et al., teaches an engageable metal seal pressure balance stab. In particular, the invention provides for the connection of a pressure-balanced stab and a manifold in which offsetting forces maintained on the stab allow it to remain in an inserted state within the manifold without the use of a significant amount of force to maintain the connection. The offsetting forces are contained within the stab through the use of C-ring seals on the stab. These seals are activated by a downward force created by an actuator. The compression of the C-rings is delayed until insertion is complete, therefore allowing an installation which does not damage the seals.
U.S. Pat. No. 6,009,950, issued on Jan. 4, 2000 to Cunningham et al., provides a subsea manifold stab with an integral check valve. This is for gas-lift injection processes and includes a built-in check valve to exclude seawater as the stab is being delivered to the subsea manifold. The check valve is a spring-loaded poppet which can be pressure-balanced with the surrounding hydrostatic forces, or alternatively, preloaded with the use of a pressurized chamber working in conjunction with a biasing spring to hold the check valve in the closed position during delivery. After insertion of the stab into the subsea manifold, the gas flow begins in the stab, which overcomes the forces of the spring and/or pressurized compartment to push the check valve into the open position to allow gas-lift flow through the manifold and down the annulus into the gas-lift valves in the well.
U.S. Pat. No. 6,200,068, issued on Mar. 13, 2001 to Bath et al., provides a hot tap fluid blaster apparatus. This apparatus serves to remove a blockage in a subsea pipeline without retrieval of the pipeline to the surface. The apparatus components include a hot tap saddle, a drill assembly, a fluid blaster assembly and a support frame. The hot tap saddle component has a first portion and a second portion, with these portions being configured to clampingly engage in a sealing relationship to the subsea pipeline. The first portion of the saddle includes a first and second opening with the first opening extending generally upwardly and configured for connecting to a drill assembly and the second opening being positioned generally at an angle to the first opening and configured for connecting to a fluid blaster assembly.
U.S. Pat. No. 7,325,598, issued on Feb. 5, 2008 to C. D. Bartlett, discloses a vacuum-assisted seal engagement for ROV-deployed equipment. The apparatus includes a bore that is sized and configured to receive a depending portion. The first and second components are exposed to a fluid which is at an ambient pressure. The method includes the steps of inserting the depending portion at least partially into the bore and then creating a bore pressure within the bore which is less than the ambient pressure.
FIG. 1 shows an conventional system in which a hydraulic hose is connected to a hot stab of an ROV. FIG. 1 shows one type of prior art system that can employ the present invention. In FIG. 1, a vessel 10 is shown floating upon the surface 11 of the body of water 12. A riser assembly 13 extends downwardly from the vessel 10 from the bottom 14 of the body of water 12. The lower elements of the riser assembly 13 include a subsea wellhead assembly 20 typically positioned on the bottom of the body of water 12 and extending downwardly into the earth formation for drilling and completion operations. The subsea wellhead assembly 20 comprises various components such as hydraulically-actuated valves 24 and 25 which are actuated by valve actuators 42 and 26, respectively. The actuators are normally controlled through shuttle valves 16 and 15 using a surface pressure source 33 via line 43 to a control pod 44 in a manner well known in the art. The hot stab 27 serves to a supply auxiliary pressurized fluid to the subsea equipment assembly. The hot stab 27 is carried by the ROV 31. The hot stab 27 is carried by or gripped, preferably in a removable manner, at one end by a manipulator arm 30 carried by the ROV 31. The manipulator arm 30 serves to direct the hot stab 27 toward a receptacle 28. The ROV 31 can be manipulated so as to cause the hot stab 26 to move into proximity with another receptacle 23.
In FIG. 1, the hot stab 27 is shown near the hydraulic valve actuator 26 which has the receptacle 28 for receiving the hot stab 27. The hot stab 27 is in fluid communication with hydraulic hose 29. The hydraulic hose 29 can be in the form of a hydraulic cable, conduit or hose. The conduit 29 supplies pressurize hydraulic fluid from a fluid source 33 on the vessel 10 by way of a winch 32 to the hot stab 27 in a manner known in the art.
The ROV 31 can be powered by a power and signal and transition cable 34 which has been reeled off the service vessel 10, in particular, from the winch 35. The ROV 31 may be remotely operated from the vessel 10 by observation of video signals received from cameras carried by the ROV 31.
As stated earlier, one of the problems with the prior art is the connection between the hydraulic hose 29 and the hot stab 27. In normal use, this connection is a relatively simple hydraulic connection. However, in view of the relatively heavy weight of the hydraulic hose 27 and the degree of manipulation carried out by the ROV 31 and the manipulator arm 30, a great deal of bending, twisting and other forces can be applied to this connection. In a relatively short period of time, leaks can occur in this connection. As such, a strong need has developed so as to provide the connector assembly such that the leaks can be avoided. As such, the number of times that the ROV 31 must traverse the distance to the surface 11 can be significantly reduced.
It is an object of the present invention to provide a connector assembly for a hot stab which serves to avoid leaks.
It is another object of the present invention to provide a connector assembly which serves to transfer loads away from the seal surface between the connector assembly of the hydraulic hose and the fluid conduit connector of the hot stab.
It is still a further object of the present invention to provide a connector assembly which minimizes the number of times that the ROV must return to the surface for leakage repair.
It is still another object of the present invention to provide a connector assembly which serves to reduce the cost associated with operating the ROV and for carrying out the necessary operations for the offshore well.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.